System Description

DESCRIPTION
1. System description
  In the KDSS (Kinetic Dynamic Suspension System), a cylinder is installed to each of the front and rear stabilizer bars. The front and rear cylinder upper chambers and the front and rear lower chambers are each connected by a pipe. The hydraulic circuit is filled with high-pressure (3 MPa) suspension fluid. The ECU controls the accumulator solenoid valves according to input signals from each sensor. The suspension roll stiffness increases and the vertical load fluctuation decreases (off-road drivability increases) through operation of this system.
2. Operation description
  1. Operation when the vehicle rolls:
    
    Fig 1: Identifying Kinetic Dynamic Suspension System Operation Description When Vehicle Rolls
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    
    When the vehicle rolls, the accumulator solenoid valves close to cause the front and rear hydraulic pressure to be equal (both upper and lower chambers) so that the front and rear pistons do not stroke. By doing this, the stabilizer bars twist as those on vehicles without a KDSS to reduce vehicle body roll.
  2. Operation when driving off-road (when one wheel rises up):
    
    Fig 2: Identifying Kinetic Dynamic Suspension System Operation Description When One Wheel Rises Up
    Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
    
    When driving off-road (when one wheel rises up), the accumulator solenoid valves open to cause the front and rear pistons to stroke in opposite directions.
    
    Because of this, the stabilizers do not twist (the effort required of the stabilizers is reduced) and allow the wheel to stroke when a shock is received from the ground.

FUNCTION OF COMPONENTS

Part Name	Function
Stabilizer bar	Reduces vehicle body roll to increase turning ability and steering stability.
Stabilizer control cylinder	Expands and contracts according to the movement of the front and rear stabilizers to dampen their movement.
Stabilizer control ECU	Closes the accumulator solenoid valves according to input signals from each sensor to cut the fluid flow to the accumulators. Turns on the KDSS indicator light in the combination meter to inform the driver when an abnormality is detected in the KDSS. When this happens, a DTC is stored.
Accumulator pressure sensor	Detects the pressure in the hydraulic circuit and sends signals to the stabilizer control ECU.
Accumulator solenoid valve	Cuts the fluid flow to the accumulator according to a signal from the stabilizer control ECU.
Accumulator	Absorbs fluid inputs from the cylinder to improve the ride quality (when the accumulator solenoid valve is open). Absorbs changes in the fluid volume caused by temperature changes (prevents high/low pressure). Provides a stable initial pressure to the system.
Speed sensor	Detects the right and left front wheel speed.
Steering angle sensor	Detects the steering speed and angle.
Acceleration sensor	Detects the lateral acceleration of the vehicle.
Stop light switch	Detects that the brake pedal is depressed in order to clear DTCs.

SYSTEM CONTROL
- The stabilizer control ECU controls the opening/closing of the accumulator solenoid valves based on the information from the speed sensors, acceleration sensor, and steering angle sensor.
- The 2 accumulator solenoid valves are opened/closed at the same time.
  
  Fig 3: Identifying Accumulator Solenoid Valve Switching Timing Graph
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
- Switching from "Close" to "Open" of the solenoid valves occurs when all sensor values deviate for a specified time from the "Close" range.